Hydrogel medical wound dressing is a novel developed wound dressing in recent years. Compared to the traditional dressing, the hydrogel can promote better healing of the wound, and relieve pain of patient. It can improve microenvironment of the wound surface, and inhibit growth of bacteria. The hydrogel is especially suitable for use in common trauma of body surface, such as abrasion, scratching, bedsore and other skin injuries. For these wounds, traditionally, the doctor generally treats them with sterile gauze and topical antibiotics. However, the gauze is prone to adhere to skin wound tissue, at time of dressing change it often destroys new epithelial and granulation tissues, causing hemorrhage, this is unbeneficial to wound healing and makes the patient painful. When the hydrogel dressing is applied onto the wound, it will not adhere to the wound, not destroying new tissue, furthermore it can kill various bacteria, avoiding wound infection. The hydrogel dressing is a kind of good wound surface dressing, it is a polymeric swelling body containing certain moisture with a three-dimensional network structure, and it has good water absorption and biocompatibility, it can closely fit with an uneven wound surface without adhesion, and reduce bacterial growth and easy to be replaced, and it can be permeated with various drug components and growth factors, promoting wound healing. The hydrogel perse has a large heat capacity, it has a mild cooling effect to the wound, and it can relieve pain of the wound. Therefore, scholars at home and abroad have made extensive research on the hydrogel dressing and obtained some achievements. At present, the hydrogel dressing occupies most part of the global dressing and bandage market.
Currently, the fibrin glue, cyanoacrylate, chitosan etc have been commercially used in wound dressing, but they respectively have shortcomings thus restricting their wide application in clinical surgery. For example, the fibrin glue is primarily derived from animal blood tissue, thus there exists a risk of blood virus infection; for cyanoacrylate, although it has a good hemostasis effect but due to its high cytotoxicity it is not best choice for wound tissue healing; for chitosan, it has a rapid hemostasis function, and can be made intovarious medical dressing products, but its poor mechanical property, high brittleness, low water-solubility have become major obstacles to its application in surgical wound dressing.
ε-polylysine is a kind of natural polymeric material forming hydrogel, it is obtained by microbial fermentation. The molecular weight of ε-polylysine is between 3 kDa and 5 kDa, being similar to the protein composition and function of nature extracellular matrix ECM), and it has significant advantage over other wound dressing material, which is in the following aspects: first, there are a large number of amino active groups on molecular chain, it binds with hydrogen ion to be positively charged and form a cationic polymer in aqueous solution or acidic environment, such cationic polymer can binds to cell surface in order to achieve trauma tissue adhesion; second, as polylysine is a natural polymeric material, having good biocompatibility, and its degradation product lysine is an essential amino acid for human, finally, polylysine is an amino acid polymer, it has good water-solubility, overcoming the issue of being difficult dissolved in water of many tissue healing materials, but polylysine has a large number of active amino groups, it binds with hydrogen ion in water solution or acidic environment to be positively charged and destroys tissue cell structure to a certain degree, and it has certain cytotoxicity, in order to make it safely used in wound tissue adhesion, it must be modified to reduce cytotoxicity.
PEG is a kind of polymer with a good water-solubility and biocompatibility, it is widely used in surface modification of biomaterial, and modification protection of polypeptide and protein drug. PEG modification has an obvious inhibitory effect to some induced apoptosis, significantly reduce content of intracellular ROS (reactive oxygen species), and make mitochondrial membrane potential ri be stable. PEG modification reduces the cytotoxicity of polylysine mainly by reducing production of intracellular ROS (reactive oxygen species), high modification degree has an obvious effect of reducing toxicity. PEG modified polylysine can significantly reduce cytotoxicity of polylysine, and the ability of reducing toxicity are obviously enhanced with increase in molecular weight and modification degree of PEG.
The hydrogel medical material currently used in wound dressing are primarily divided into chemically synthesized and biopolymer material, but there are many shortcomings such as low mechanical strength, poor biocompatibility, and high cytotoxicity during formation of hydrogel material.